The document (pictured above) was shared with AppleInsider, and is said to show that available vacation time drops significantly from Sept. 15, and doesn’t pick up again until Sept. 28. The website explains:

The image provided shows the calendar being accessed via virtual private network from an internal Apple employee domain. Potentially identifying portions of the picture have been cropped out.

T-Mobile recently blocked out employee vacations for Sept. 20 to Sept. 22, potentially signalling that the new iPhone handsets could make an appearance in stores nationwide during this three-day period. That AppleCare support staff are expected to be on-hand from Sept. 15 suggests that Apple will announce its next-generation iPhones – and potentially release iOS 7 – around Sept. 15, however.